Always use xcrun as a fallback for finding binaries on macOS (#1998)

Author: matthewbastien

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 - When editing .sourcekit-lsp/config.json use the JSON schema from the toolchain ([#1979](https://github.com/swiftlang/vscode-swift/pull/1979))
 
+### Fixed
+
+- Fix extension failing to find `lldb-dap` when `swift.path` points at an Xcode toolchain ([#1998](https://github.com/swiftlang/vscode-swift/pull/1998))
+
 ## 2.14.2 - 2025-12-07
 
 ### Fixed

src/toolchain/toolchain.ts

@@ -436,25 +436,25 @@ export class SwiftToolchain {
      * Search for the supplied executable in the toolchain.
      */
     private async findToolchainExecutable(executable: string): Promise<string> {
-        if (process.platform === "win32") {
-            executable += ".exe";
-        }
-        // First search the toolchain's 'bin' directory
-        const toolchainExecutablePath = path.join(this.toolchainPath, "bin", executable);
-        if (await pathExists(toolchainExecutablePath)) {
-            return toolchainExecutablePath;
-        }
-        // Fallback to xcrun if the active toolchain comes from Xcode/CommandLineTools
-        if (
-            this.manager === "xcrun" ||
-            (this.manager === "swiftly" && (await Swiftly.inUseVersion()) === "xcode")
-        ) {
-            const { stdout } = await execFile("xcrun", ["--find", executable]);
-            return stdout.trim();
-        }
-        throw new Error(
-            `Failed to find ${executable} within Swift toolchain '${this.toolchainPath}'`
-        );
+        let cause: unknown = undefined;
+        try {
+            if (process.platform === "win32") {
+                executable += ".exe";
+            }
+            // First search the toolchain's 'bin' directory
+            const toolchainExecutablePath = path.join(this.toolchainPath, "bin", executable);
+            if (await pathExists(toolchainExecutablePath)) {
+                return toolchainExecutablePath;
+            }
+            // Fallback to using xcrun if we're on macOS
+            if (process.platform === "darwin") {
+                const { stdout } = await execFile("xcrun", ["--find", executable]);
+                return stdout.trim();
+            }
+        } catch (error) {
+            cause = error;
+        }
+        throw new Error(`Failed to find ${executable} within Swift toolchain`, { cause });
     }
 
     private basePlatformDeveloperPath(): string | undefined {

src/utilities/utilities.ts

@@ -153,6 +153,14 @@ export async function execFile(
             options.env = { ...(options.env ?? process.env), ...runtimeEnv };
         }
     }
+    if (Object.keys(configuration.swiftEnvironmentVariables).length > 0) {
+        // when adding environment vars we either combine with vars passed
+        // into the function or the process environment vars
+        options.env = {
+            ...(options.env ?? process.env),
+            ...configuration.swiftEnvironmentVariables,
+        };
+    }
     options = {
         ...options,
         maxBuffer: options.maxBuffer ?? 1024 * 1024 * 64, // 64MB
@@ -261,14 +269,6 @@ export async function execSwift(
         swift = toolchain.getToolchainExecutable("swift");
         args = toolchain.buildFlags.withAdditionalFlags(args);
     }
-    if (Object.keys(configuration.swiftEnvironmentVariables).length > 0) {
-        // when adding environment vars we either combine with vars passed
-        // into the function or the process environment vars
-        options.env = {
-            ...(options.env ?? process.env),
-            ...configuration.swiftEnvironmentVariables,
-        };
-    }
     options = {
         ...options,
         maxBuffer: options.maxBuffer ?? 1024 * 1024 * 64, // 64MB

test/unit-tests/toolchain/toolchain.test.ts

@@ -99,7 +99,7 @@ suite("SwiftToolchain Unit Test Suite", () => {
                 });
 
                 await expect(sut.getLLDBDebugAdapter()).to.eventually.be.rejectedWith(
-                    "Failed to find lldb-dap within Swift toolchain '/Library/Developer/Toolchains/swift-6.0.1-RELEASE.xctoolchain/usr'"
+                    "Failed to find lldb-dap within Swift toolchain"
                 );
             });
 
@@ -153,6 +153,39 @@ suite("SwiftToolchain Unit Test Suite", () => {
                     "/Library/Developer/CommandLineTools/usr/bin/lldb-dap"
                 );
             });
+
+            test("returns the path to lldb-dap if it exists within an Xcode toolchain selected using swift.path", async () => {
+                mockFS({
+                    "/Applications/Xcode.app/Contents/Developer": {
+                        Toolchains: {
+                            "XcodeDefault.xctoolchain": {},
+                        },
+                        usr: {
+                            bin: {
+                                "lldb-dap": mockFS.file({
+                                    content: "",
+                                    mode: 0o770,
+                                }),
+                            },
+                        },
+                    },
+                });
+                mockedUtilities.execFile.withArgs("xcrun", ["--find", "lldb-dap"]).resolves({
+                    stdout: "/Applications/Xcode.app/Contents/Developer/usr/bin/lldb-dap",
+                    stderr: "",
+                });
+                const sut = createSwiftToolchain({
+                    manager: "unknown",
+                    swiftFolderPath:
+                        "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr",
+                    toolchainPath:
+                        "/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr",
+                });
+
+                await expect(sut.getLLDBDebugAdapter()).to.eventually.equalPath(
+                    "/Applications/Xcode.app/Contents/Developer/usr/bin/lldb-dap"
+                );
+            });
         });
 
         suite("Linux", () => {
@@ -189,7 +222,7 @@ suite("SwiftToolchain Unit Test Suite", () => {
                 });
 
                 await expect(sut.getLLDBDebugAdapter()).to.eventually.be.rejectedWith(
-                    "Failed to find lldb-dap within Swift toolchain '/toolchains/swift-6.0.0/usr'"
+                    "Failed to find lldb-dap within Swift toolchain"
                 );
             });
         });
@@ -228,7 +261,7 @@ suite("SwiftToolchain Unit Test Suite", () => {
                 });
 
                 await expect(sut.getLLDBDebugAdapter()).to.eventually.be.rejectedWith(
-                    "Failed to find lldb-dap.exe within Swift toolchain '/toolchains/swift-6.0.0/usr'"
+                    "Failed to find lldb-dap.exe within Swift toolchain"
                 );
             });
         });